A test adapter can have numerous contacts for engaging the leads of a PLCC (Plastic Leaded Chip Carrier), which is a flat four-sided carrier having leads extending from the sides. The contacts on the test adapter route electrical signals from closely spaced leads on the carrier to test points sized and spaced for standard industry connectors. One type of prior art adapter is aligned with the carrier by aligning several positioning pins on the adapter with corresponding holes in the carrier, and then slipping attachment hooks under two opposing corners of the carrier. The outside of the carrier is then pushed down to move its contacts onto the leads of the carrier. One shortcoming of such prior art adapter is that there may be poor alignment of the adapter with the carrier because of slight irregularities in the carriers. Also, uneven pressure can be applied during actuation, which sometimes causes an adapter contact to short two of the carrier leads.
Another type of prior art adapter has four frames that are pivoted apart by squeezing two sections between the finger and thumb in the manner of a closepin, while a cam mechanism opens the other two sides. The device is placed on the carrier and released to move the contacts against the carrier leads. A metal spring applies the necessary clamping force. This has the disadvantage that there is assymetrical clamping force, resulting in the possibility of misalignment, the adapter contacts do not make wiping action with the carrier leads, and a metal spring is required so an all-plastic adapter (except for the contacts) is not realized.
An adapter which assured alignment of its contacts with the carrier leads, which assured uniform clamping forces around the carrier, and which has constructed compactly and at low cost without the need for metal springs or other metal parts other than the contacts, would be of considerable value.